SCI32: Add low resolution constants

In a few places in the graphics system, fixed low-resolution values
are used instead of the game script resolution.

3 files changed, 28 insertions, 6 deletions

diff --git a/engines/sci/graphics/celobj32.cpp b/engines/sci/graphics/celobj32.cpp
index af5ee3abbc..befa5cda18 100644
--- a/engines/sci/graphics/celobj32.cpp
+++ b/engines/sci/graphics/celobj32.cpp
@@ -799,8 +799,8 @@ CelObjView::CelObjView(const GuiResourceId viewId, const int16 loopNo, const int
 	if (_scaledWidth == 0 || _scaledHeight == 0) {
 		byte sizeFlag = data[5];
 		if (sizeFlag == 0) {
-			_scaledWidth = 320;
-			_scaledHeight = 200;
+			_scaledWidth = kLowResX;
+			_scaledHeight = kLowResY;
 		} else if (sizeFlag == 1) {
 			_scaledWidth = 640;
 			_scaledHeight = 480;
@@ -985,8 +985,8 @@ CelObjPic::CelObjPic(const GuiResourceId picId, const int16 celNo) {
 		_scaledWidth = sizeFlag1;
 		_scaledHeight = sizeFlag2;
 	} else if (sizeFlag1 == 0) {
-		_scaledWidth = 320;
-		_scaledHeight = 200;
+		_scaledWidth = kLowResX;
+		_scaledHeight = kLowResY;
 	} else if (sizeFlag1 == 1) {
 		_scaledWidth = 640;
 		_scaledHeight = 480;
diff --git a/engines/sci/graphics/celobj32.h b/engines/sci/graphics/celobj32.h
index 6e401b3df4..e405592b5f 100644
--- a/engines/sci/graphics/celobj32.h
+++ b/engines/sci/graphics/celobj32.h
@@ -31,6 +31,20 @@
 namespace Sci {
 typedef Common::Rational Ratio;
 
+// SCI32 has four different coordinate systems:
+// 1. low resolution, 2. game/script resolution,
+// 3. text/bitmap resolution, 4. screen resolution
+//
+// In CelObj, these values are used when there is
+// no baked in resolution of cels.
+//
+// In ScreenItem, it is used when deciding which
+// path to take to calculate dimensions.
+enum {
+	kLowResX = 320,
+	kLowResY = 200
+};
+
 enum CelType {
 	kCelTypeView  = 0,
 	kCelTypePic   = 1,
diff --git a/engines/sci/graphics/screen_item32.cpp b/engines/sci/graphics/screen_item32.cpp
index c0b3240c7e..d2673d40b3 100644
--- a/engines/sci/graphics/screen_item32.cpp
+++ b/engines/sci/graphics/screen_item32.cpp
@@ -273,7 +273,9 @@ void ScreenItem::calcRects(const Plane &plane) {
 		// Cel may use a coordinate system that is not the same size as the
 		// script coordinate system (usually this means high-resolution
 		// pictures with low-resolution scripts)
-		if (celObj._scaledWidth != scriptWidth || celObj._scaledHeight != scriptHeight) {
+		if (celObj._scaledWidth != kLowResX || celObj._scaledHeight != kLowResY) {
+			// high resolution coordinates
+
 			if (_useInsetRect) {
 				const Ratio scriptToCelX(celObj._scaledWidth, scriptWidth);
 				const Ratio scriptToCelY(celObj._scaledHeight, scriptHeight);
@@ -345,6 +347,8 @@ void ScreenItem::calcRects(const Plane &plane) {
 			_ratioX = scaleX * celToScreenX;
 			_ratioY = scaleY * celToScreenY;
 		} else {
+			// low resolution coordinates
+
 			int displaceX = celObj._displace.x;
 			if (_mirrorX != celObj._mirrorX && _celInfo.type != kCelTypePic) {
 				displaceX = celObj._width - celObj._displace.x - 1;
@@ -582,7 +586,9 @@ Common::Rect ScreenItem::getNowSeenRect(const Plane &plane) const {
 		displaceX = celObj._width - displaceX - 1;
 	}
 
-	if (celObj._scaledWidth != scriptWidth || celObj._scaledHeight != scriptHeight) {
+	if (celObj._scaledWidth != kLowResX || celObj._scaledHeight != kLowResY) {
+		// high resolution coordinates
+
 		if (_useInsetRect) {
 			Ratio scriptToCelX(celObj._scaledWidth, scriptWidth);
 			Ratio scriptToCelY(celObj._scaledHeight, scriptHeight);
@@ -616,6 +622,8 @@ Common::Rect ScreenItem::getNowSeenRect(const Plane &plane) const {
 		mulinc(nsRect, celToScriptX, celToScriptY);
 		nsRect.translate(_position.x - displaceX, _position.y - displaceY);
 	} else {
+		// low resolution coordinates
+
 		if (!scaleX.isOne() || !scaleY.isOne()) {
 			mulinc(nsRect, scaleX, scaleY);
 			// TODO: This was in the original code, baked into the